Heather VanHeuvelnUniversity of FloridaMasters in Agronomyheatherv@ufl.edu

Chinese Tallowtree (Triadica sebifera (L.) Small)

Seed Biology: An Evaluation of Seed fill, Germination and Seed Bank

Longevity

•Native to Southeast Asia•Characteristics:▫Deciduous, monecious▫6-15 meters ▫Matures quickly

+100,000 seeds (Lin et. al, 1958)

Dispersed byhydrochory zoochoryvelocity~1-1.2 km/yr. (Wang et

al. 2011, Renne et al. 2000)

Biology CHUCK BARGERONGREEN DEANE

JIM CONRAD

•Introduced in mid 1700’s.•Monotypic stands in 18-29

years (Wang et al. 2011 & Bruce et al. 1995)

•Roadways, waterways, forest edges•Cannot tolerate severe

winters/dry conditions

USA Distribution

Eddmaps.orgPlants.usda.gov

•Habitat transformer•Displaces native and

agronomic species•Listed Species▫Category 1 FLEPPC Invasive

Species▫FDACS Noxious Weed

Problematic

•Germination requirements•Seed Bank longevity▫Unknown (edis.ifas.ufl pub. Ag148)

▫Dormancy? 0-100 years? (Zang & Lin, 1994)

•Overall highly variable results…

Small sample sizes Varying collection dates Regional variation(Cameron et al., 2000)

Seed Biology:

Determine…in Central Florida.

1. seedling emergence patterns and seed bank longevity2. after ripening affects on seed germination and viability3. seed fill characteristics

Objectives

Seed Exclusion Frames•2 Field Sites▫Gainesville, FL▫Jay, FL

•1x1 meter frames▫Fine and wide mesh screen

•Checked monthly

Seedling Emergence and Seed Bank Longevity

Timeline of Exclusion Frame Placements

2014

January• Gainesville; 10 frames

2015

February• Gainesville;

+10 framesMarch• Jay; 10 frames

Emergence•Timing varies by location▫Later for northern location

•Occurs over 2-3 months in spring

Results: Emergence before 1st Season of Exclusion

Mar Apr May Jun Jul0

10

20

30

40

50

First Year Mean Seedling Emergence Gainesville & Jay Florida

2014 Gainesville 2015 Gainesville 2015 Jay

MonthM

ean

Emer

genc

e (S

eedl

ings

/m2)

•Emergence trends continued•2nd year emergence decline▫100% March▫82% April ▫50% May

•Dormancy or quiescence?

Results: 1 Season of Seed Exclusion

Feb

AprJun

0

5

1st Year Seed ExclusionSeedling Emergence

Gainesville, FL

2014 2015Month

Mea

n Em

erge

nce

(See

dlin

gs /

m2)

•After-ripening affects of time on tree & off tree storage▫Germination

Growth Chamber Time-event analysis

▫Viability Non-germinated seed TZ Test Pearson’s chi-square Test

Germination StudiesHarvest

Bulk Sample

Off Tree6 Month Storage

5°C

Ambient

No Storage(Fresh)

On TreeNo Storage

(Fresh)

•Harvests▫After capsule split▫2 weeks 4 total harvests

•Sampled 10-15 trees▫Seeds cleaned/sorted▫Bulk sample 100 seeds/tree 100 seeds/treatment

Seed Collection

Seedoilcrops.org

•Planting▫200 cell tray

2.29 cm. x 2.29 cm. x 4.5 cm.▫1 cm. below surface▫Sub-surface watered

•Growth chamber ▫15°C dark (15 hrs.)▫27°C light (9 hrs.)

Germination Tests

Emerged

Germinated

Testing Terminated

Viability Testing

Results: On Tree After Ripening•Germination

No Significant difference between harvests

P value= 0.6608 at α=0.05•Viability▫No significant difference

between harvests Non-germinated seed α=0.005

0

30

60

90

Components of Viability Fresh Seed

Germ TZ Viable NonViableHarvest (wks.)

Rela

tive

freq

uenc

y (%

)

2 4 6 8

•Viability▫No Significant difference Non-germinated; α =0.005All treatments~41% viable~51% non-viable

•No significant difference in harvests▫1st Harvest removed

•Germination▫6 Month Storage (Ambient & 5°C) Significant 71% decrease in

germination of viable seed fraction (P=0.01)

Significant 9 day increase in mean germination timing(31st day vs 40th day)

Results: Off tree storage

Components of Viability Pooled-H1 Means with Standard Errors

n GerminatedRelative Frequency(Viable portion) TZ Viable Non-viableGerm. %

Fresh 300 13.33 ± 1.53* 28.57* 33.33 ± 3.51 53.33 ± 4.16

6 Month Storage

Ambient 300 4 ± 2.64 7.84 47 ± 2 49 ± 4.36

5°C 300 4.33 ± 2.89 8.90 44.33 ± 4.04 51.33 ± 6.81

Significantly different within column *α=0.05;

Components of Viability Pooled-H1 Means with Standard Errors

n GerminatedRelative Frequency(Viable portion) TZ Viable Non-viableGerm. %

Fresh 300 13.33 ± 1.53* 28.57* 33.33 ± 3.51 53.33 ± 4.16

6 Month Storage

Ambient 300 4 ± 2.64 7.84 47 ± 2 49 ± 4.36

5°C 300 4.33 ± 2.89 8.90 44.33 ± 4.04 51.33 ± 6.81

Significantly different within column *α=0.05;

Components of Viability Pooled-H1 Means with Standard Errors

n GerminatedRelative Frequency(Viable portion) TZ Viable Non-viableGerm. %

Fresh 300 13.33 ± 1.53* 28.57* 33.33 ± 3.51 53.33 ± 4.16

6 Month Storage

Ambient 300 4 ± 2.64 7.84 47 ± 2 49 ± 4.36

5°C 300 4.33 ± 2.89 8.90 44.33 ± 4.04 51.33 ± 6.81

Significantly different within column *α=0.05;

71% Germination

•Random 100 seed sample•X ray imaging•Ohio State University•Visually rate seed fill

Seed Fill 100% EMPTY

<100% PREDATION

•37% of sample <100% Fill▫Lack of embryo

development▫Predation

•72% of non-viable seeds▫(H1 not included)

Seed fill: Results

100% <100%0

10

20

30

40

50

60

70

63

37

Gainesville, FL Seed Fill

Percent FillFr

eque

ncy

(%)

•Viable seed frequency consistent▫Possible indicator of

dormancy

•Incomplete seed fill ▫72% of final non-viable

seed▫R strategist trait▫Treatment units increased

•No immediate effect of on tree after ripening

•6 Months of Storage▫Increases germination

timing▫Decreases total

germination

Conclusions: Germination and Seed Fill Studies

•Seed Bank Longevity▫Disturbance treatment▫Monitor site conditions

•Germination testing▫Aril’s influence on

germination

Future Projects

▫Florida Park Service Paynes Prairie Preserve State Park

Andrea Christman San Felasco Hammock Preserve

State Park Gary Kreitzer (AmeriCorps)

• Funding Sources▫University of Florida▫Florida Fish and Wildlife

Conservation Commission

• Volunteers and Facilitators▫University of Florida

Agronomy Graduate Students Justin McKeithen Dr. Greg Macdonald Dr. Kimberly Bohn Dr. Hector Perez

▫University of Ohio Dr. Susan Stieve Dr. Pablo Jourdan

Acknowledgements

Questions?Heather VanHeuveln

heatherv@ufl.edu